– 27 –
5-3. Bird’s nest reducing device
When the bird’s nest reducing device is used, the needle thread is trimmed at the beginning of sewing.
As a result, the needle thread that remains on the reverse side of material is shortened, thereby reduc-
ing the formation of so-called bird’s nest (thread tangling) to contribute neater finish of the reverse side
of material. The trimmed thread is blown out from the righthand side by the air blower to be collected in
the cloth chip bag.
(1) In the case the bird’s nest reducing device
is turned ON, it is necessary to adjust the
needle thread length remaining at the needle
at the beginning of sewing to 40 to 50 mm
as in the case of operating the thread clamp
device. If the aforementioned needle thread
length is too long, the trimmed thread may
be entangled in the hook, causing the sewing
machine to be locked. On the other hand, if
the aforementioned needle thread length is
too short, the trimmed thread (thread waste)
cannot be collected but drop on the floor.
40 to 50mm
(2) Empty the cloth chip collection bag on a regu-
lar basis.
1.
Be sure to use the wiper whenever the bird’s nest reducing device is used. ?If the inter
-
mediate presser presses the needle thread (as shown in the figure given below), only
the bobbin thread will be trim and the sewing machine will fail to produce stitches at
the beginning of next sewing. As a result, the sewing machine cannot perform sewing
at the beginning of sewing. Enable / disable of the wiper can be changed over with the
memory switch U051.
2. In the case the bird’s nest reducing device is disabled with the memory switch U035,
or in the case the shorter-thread remaining type is selected with the memory switch
U322, the bird’s nest reducing operation cannot be selected. Refer to
moving knife and counter knife (Shorter-thread remaining type)" p.138
for the short
-
er-thread remaining type model.
If the thread tension is excessive
-
ly low at the beginning of sewing,
the length of needle thread to be
trimmed will be too long. In such a
case, the trimmed thread cannot be
blown out by the air blower, but will
be liable to remain inside the hook.
The thread tension to be applied to
the thread when sewing three stitch
-
es (at the maximum) at the beginning
of sewing can be set with the mem-
ory switches U019 to U024. Refer to
"II-2-6-2. Memory switch" p.78
.
